Centrifugal separator

ABSTRACT

A centrifugal separator ( 10 ) for separating separable constituents of a fluid to be separated, includes a body ( 12 ) rotatable about an axis, the body having a cavity ( 22 ) therein. A divider ( 28 ) divides the cavity into a first sub-cavity ( 24 ) arranged for fluid to flow in a direction having a radial component and a second sub-cavity ( 26 ) arranged for fluid to flow in a direction having a component that is towards the axis of rotation. An inlet ( 58 ) leads into the first sub-cavity at or near the axis of rotation of the body. A first outlet ( 52 ) is in communication with a settling region ( 34 ) of the cavity between or connecting the first sub-cavity to the second sub-cavity. A second outlet ( 50 ) leads from the second sub-cavity at or near the axis of rotation of the body.

FIELD OF THE INVENTION

The present invention relates to a separator for separating separableconstituents in a fluid.

BACKGROUND OF THE INVENTION

It is known to use a centrifuge to separate suspended particles in aliquid as well as insoluble liquids. Most centrifuges rely on batchoperation whereby a quantity of liquid for separation is inserted in acentrifuge, the centrifuge rotated separating the constituents in theliquid, the centrifuge stopped and the separated constituents removed.

Alternatively a screen or filter is used whereby particles of a sizegreater than the screen or filter are trapped within the centrifuge andparticles of a lesser size pass through the screen or filter and arethereby separated. The problem with this type of separator is that thescreen or filter can become clogged or blocked and must be regularlycleaned. A screen or filter can also impede flow.

The present invention provides a new centrifugal separator that is ableto be operated either on a batch or continuous basis and does notrequire a screen or filter that may become blocked.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a centrifugalseparator for separating separable constituents of a fluid to beseparated, including:

a body rotatable about an axis, the body having a cavity therein;

a divider dividing the cavity into a first sub-cavity arranged for fluidto flow in a direction having a radial component and a second sub-cavityarranged for fluid to flow in a direction having a component that istowards the axis of rotation;

an inlet leading into the first sub-cavity at or near the axis ofrotation of the body;

a first outlet in communication with a settling region of the cavitybetween or connecting the first sub-cavity to the second sub-cavity; and

a second outlet leading from the second sub-cavity at or near the axisof rotation of the body;

whereby in use, fluid to be separated enters the cavity via the inlet,rotation of the body and the fluid therein causes a centrifugal force tobe applied to fluid flowing through the cavity, a first constituent ofthe fluid tends to collect in the settling region and a secondconstituent of the fluid tends to flow into the second sub-cavity, thesecond constituent in the second sub-cavity exits the cavity via thesecond outlet and the first constituent collected in the settling regionexits the cavity via the first outlet.

Preferably a third sub-cavity connects the settling region to the firstoutlet. The third sub-cavily is arranged for fluid flow in a directionhaving a component that is towards the axis of rotation of the body. Ina first embodiment, the first outlet is at or near the axis of rotation.Preferably the third sub-cavity is separated into a plurality ofchambers by dividing walls, with each chamber extending towards the axisof rotation.

Preferably the size of the cavity decreases radially from the axis ofrotation. Preferably the divider is shaped such that the shape of thefirst sub-cavity increases along the path of flow of fluid though thefirst sub-cavity. Preferably the size of the second sub-cavity decreasesalong the path of flow of fluid through the second sub-cavity.Preferably the divider is shaped to space the first sub-cavity from thesecond sub-cavity.

Preferably the first sub-cavity is provided with a plurality of radiallyextending fins. Preferably the first sub-cavity is divided into aplurality of chambers by the fins. Preferably the second sub-cavity isprovided with a plurality of radially extending second fins. Preferablythe second sub-cavity is divided into a plurality of chambers by thesecond fins. Preferably each first fin is integrally formed with acorresponding one of the second fins.

Preferably the separator includes a drive means for rotating the body.Preferably the speed of rotation of the body is controlled, whereby theextent of separation of the constituents can be controlled.

Preferably the separator includes a means for controlling the rate offlow of fluid to be separated in through the inlet. Preferably theseparator includes a means for controlling the rate of flow of fluidfrom the first outlet. Preferably the separator includes a means forcontrolling the rate of flow of the fluid from the second outlet.

Preferably a shaft extends through the axis of rotation, the bodyarranged to be rotated by rotation of the shaft. Preferably the shaftextends through the body.

In a second embodiment, the settling region includes a collection regionfor holding the collected first constituent until it is removed via thefirst outlet. Preferably the collection region is spaced from the axisof rotation.

Preferably the body is substantially disc shaped. Preferably the bodyincludes a first part and a second part. In a third embodiment, theparts are in the form of discs. Preferably the discs are separable.Preferably the first outlet is provided by a gap between the body partswhen the parts are separated. Preferably the size of the gap isadjustable.

Preferably the divider is in the form of a radially extending planardisc. In one variation a circumferential region of the divider includesa first flange extending transversely to a radial line extending fromthe axis of rotation. Preferably the circumferential region includes asecond flange extending transversely to the radial line from the axis ofrotation and at an angle to the first flange greater than the angle ofthe first flange to the divider.

Preferably the inlet is provided with a raceway. Preferably the firstoutlet is provided with a raceway.

Preferably the separator includes a first collection means forcollecting the first constituent as it exits the first outlet.Preferably the separator includes a second collection means forcollecting the second constituent as it exits the second outlet.

In another variation, the collection region is contained within a bulbshaped portion of the body.

Preferably a separation zone precedes the collection region in thecourse of flow of fluid. Preferably the separation zone is divided intoan inner separation zone and an outer separation zone by a partingmeans. Preferably the parting means is a circular knife. Preferably thecollection region follows the outer separation zone in the course offlow of the fluid. Preferably a third outlet leads from the innerseparation zone. Preferably the separator includes a third collectionmeans for collecting the constituents exiting the third outlet.

Preferably the inlet extends the inside of the shaft. Preferably thesecond outlet extends into the inside of the shaft. Preferably the thirdoutlet extends into the inside of the shaft.

Preferably the first outlet is closed and sealed by a seal in the gapbetween the parts of the body when the gap between the parts is closed.More preferably the first outlet is open when the gap between the partsis opened. Alternatively the gap is in communication with a valve/sealmeans. Preferably the first outlet is unsealed and open when the gapbetween the parts is moved to be partly closed. More preferably thefirst outlet is closed and sealed by the seal means when the gap betweenthe parts is opened.

In the present specification, the term “fluid to be separated” is to beunderstood to mean an emulsion, suspension, mixture, or the like ofconstituents such as liquid and gas, liquid and liquid, gas and solidparticles, liquid and solid particles, solid particles and solidparticles, gas and gas or combinations thereof where the constituentsare to be separated from one another. Typically, the constituents willbe immiscible.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to provide a better understanding, a preferred embodiment ofthe present invention will now be described, in detail, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional side elevation of a centrifugal separator inaccordance with the present invention;

FIG. 2 is a cross-sectional view of the section 2-2 of the separator ofFIG. 1;

FIG. 3 is a cross-sectional view of the section 3-3 of the separator ofFIG. 1;

FIG. 4 is an enlarged cross-sectional side elevation of a top portion ofthe separator of FIG. 1 showing an upper bearing;

FIG. 5 is an enlarged cross-sectional side elevation of a portion ofFIG. 1 showing a lower bearing;

FIG. 6 is a cross-sectional side elevation of a preferred embodiment ofthe separator of the present invention;

FIG. 7 is a cross-section side elevation of a lower section of theseparator of FIG. 6;

FIG. 8 is a plan view of the section A-A of FIG. 6 showing the lowersection of FIG. 7;

FIG. 9 is a cross-sectional side elevation of an upper section of theseparator of FIG. 6;

FIG. 10 is a plan view looking from the section B-B of FIG. 6 of theupper section of FIG. 9;

FIG. 11 is a cross-sectional view of a first set of paddles of theseparator of FIG. 6;

FIG. 12 is a cross-sectional view of a divider of the separator of FIG.6;

FIG. 13 is a cross-sectional view of a second set of paddles of theseparator of FIG. 6;

FIG. 14 is a part cross-sectional side elevation of an alternativeseparator in accordance with the present invention;

FIG. 15 is a part cross-sectional side elevation of a furtheralternative separator in accordance with the present invention;

FIG. 16 is a part cross-section side elevation of yet anotheralternative separator in accordance with the present invention;

FIG. 17 is a side elevation of a separator housed in a chassis for use;

FIG. 18 is a cross-sectional side view of a separator mounted on a jackwithin the chassis of FIG. 17;

FIG. 19 is a part cross-sectional side elevation of the separator ofFIG. 6 in use;

FIG. 20 is a part cross-sectional side elevation of yet anotheralternative separator in accordance with the present invention;

FIG. 21 is a cross-sectional side elevation of a further embodiment of aseparator in accordance with the present invention;

FIG. 22 is a part cross-sectional side elevation of the separator ofFIG. 21;

FIG. 23 is a part cross-sectional side elevation of the separator ofFIG. 21, with an alternative seal of an outlet;

FIG. 24 is a part cross-sectional side elevation of the separator ofFIG. 21, with another alternative seal of the outlet, in a closedconfiguration; and

FIG. 25 is a part cross-sectional side elevation of the separator andseal of FIG. 24, with the outlet in an open configuration.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, there is shown a separator 10 which includes a body12 coupled to or integrally formed with a shaft 14. The body 12 andshaft 14 are rotatably mounted to a frame 16, with the shaft alignedwith the axis of rotation.

The body 12 includes a first part 18 and a second part 20 securedtogether by bolts 19. Inside the body 12 is a cavity 22, notionallydivided into a first sub-cavity 24 and a second sub-cavity 26 by a firstdivider 28, and a third sub-cavity 38 by a second divider 30. The firstsub-cavity 24 is regarded as a part of the cavity 22 having a radiallyextending component. The second sub-cavity 26 is regarded as a part ofthe cavity 22 having a directional component towards the axis ofrotation of the body 12 through which some of the separated fluid flows.The third sub-cavity 38 is regarded as a part of the cavity 22 alsohaving a directional component towards the axis of rotation of the body12 through which the rest of the separated fluid flows. Fluid willgenerally be travelling in a direction having a radial component when itis within the first sub-cavity 24 and in a direction having a componenttowards the axis of rotation when it is within the second sub-cavity 26and third sub-cavity 38. Either between or coinciding with the firstsub-cavity 24 and the second sub-cavity 26, is a settling region 34 thatleads to a first outlet 52 via the third sub-cavity 38. The secondsub-cavity 26 leads to an outlet 50 in line with the axis of rotation.Outlet 52 from the body is close to the axis of rotation.

An inlet 58 into the cavity 22 (and to the first sub-cavity 24)coincides with the axis of rotation.

The peripheral surfaces of the first and second sub-cavities 24 and 26are somewhat conical and slope through the settling region 34 towards anentry to the third sub-cavity 38. This allows heavier constituents toflow down the slopes to the entry.

The divider 28 is shaped to minimise turbulence within the cavity 22 andto provide an expanding cross-sectional area as fluid flows through thefirst sub-cavity 24. These features encourage settling within thesettling region 34 as fluid travels through the separator 10. Thedivider 28 is also shaped to provide a narrowing cross-sectional area asfluid travels through the second sub-cavity 26 towards the axis ofrotation, which also encourages settling.

A plurality of fins 32 and 36 are provided in the first and secondsub-cavities 24 and 26. These fins 32 and 36 are preferably integrallyformed such that a single fin 35 forms first 32 and second 36 finswithin the first and second sub-cavities 24 and 26, respectively. Thefins 35 are shown extending radially in FIG. 2. The fins 35 partitionthe first sub-cavity into a plurality of first channels 70 and thesecond sub-cavity into a plurality of second channels. They also impartrotational velocity to fluid travelling through the first sub-cavity 24while also further minimising turbulence of the fluid by reducing slipin the fluid. When the fluid enters the second sub-cavity 26, the fins35 recover the rotational velocity of the fluid passing through thesecond channels thereby conserving energy. As a result, a large portionof the energy required to rotate fluid at a high rotational velocity isrecovered, so that the overall energy required to be input is less thanwould be required by a screen or filter centrifuge.

The third sub-cavity 38 is formed of a plurality of passageways 72 inbetween islands 74. Each of the passageways 72 is able to recoverrotational energy imparted as the constituent flows through the thirdsub-cavity 38 to the first outlet 52. This further contributes to theconservation of energy.

The shaft 14 is coupled to a spindle 44 around which a belt can beplaced. A motor rotates the belt and thus the separator 10.

Referring to FIG. 4, the shaft 14 and upper portion of the body 12 isrotatably coupled to a top member 62 of the frame 16 by bearings 46. Thetop member 62 is spaced from a bottom member 64. Separating the topmember 62 and bottom member 64 is a cylindrical cage member 66 whichprovides a protective barrier around the rotating body 14. The rotatingbody 14 can be rotating at high velocities. The frame 16 is not onlyused for mounting purposes, it is also used for safety purposes. Theinside of the cage member 66 my be lined with a thermally resistantmaterial, which may act as a break if the body broke free.

Referring to FIG. 5, a bottom of the separator body 12 is coupled to thebottom member 62 by a bearing 48.

The divider 28 may be formed of a very lightweight material so that ithas a specific gravity less than the fluid flowing through the separator10. This will urge the divider 28 to remain in-line with the axis ofrotation of the body 12. The cavity 22 can be formed by molding theshape of the inside of the body 12 to the desired shape of the inside ofthe cavity 22. Preferably the shape will be molded from a material 40and 42 having a specific gravity greater than the fluid to be separated.

The method of use and operation of this embodiment of the presentinvention will now be described with reference to the accompanyingdrawings.

The fluid to be separated contains at least a first constituent and asecond constituent. The fluid to be separated enters the inlet 58. Aswirl device may be provided at the inlet 58 to provide the fluid to beseparated with an initial rotational impedus. The fluid to be separatedis divided by a point 60 of the divider 28. The fluid to be separatedtravels substantially radially at first within each of the passages 70between the first fins 32 where it increases in rotational velocity asit moves radially through the first sub-cavity 24.

The fluid to be separated then enters an expanding portion of the firstsub-cavity 24. Due to centrifugal force applied to the rotating fluid tobe separated, a high artificial gravity is experienced by the fluid tobe separated. Due to the artificial gravity and assisted by theturbulence minimising features described above, particles of a higherspecific gravity will tend to move along the peripheral surface in thesettling zone 34, into the entry to the third sub-cavity. Particles witha higher specific gravity are regarded as the first constituent and willtend to congregate and move towards the extreme most radial perimeterwithin the settling zone, ie. the entry to the third sub-cavity. Thesecond constituent with a lesser specific gravity will tend to “float”towards the axis of rotation. This second constituent then moves intothe second sub-cavity 26 and travels through the second channels betweenthe fins 36 moving closer towards the axis of rotation. The firstconstituent enters the opening of the passageways 72 in the thirdsub-cavity and travels through passages 72 back towards the axis ofrotation. As the first constituent and the second constituent traveltowards the axis of rotation, rotational energy is recovered by fins 26or islands 74. The first constituent then exits the first outlet 52 andtravels into a pipe 56 where it is then taken away. The secondconstituent exits the separator by the second outlet 50 where it travelsthrough pipe 54 and is then taken away.

The fluid to be separated is preferably pressure fed into the separator10 to assist in the flow through of the constituents. In particular, theseparated first constituent can become highly viscous or paste-likedepending on its nature, so pressurisation assists to avoid clogging. Inaddition, suction could be applied to the outlet 52.

Depending on the speed of rotation, the degree of separation of theconstituents can be controlled. Furthermore, separated secondconstituent exiting pipe 54 can be recycled through the separator oranother separator to remove a further amount of first constituent, ifany, remaining in separated fluid. Equally, the separated firstconstituent could be recycled to further refine the degree ofseparation.

Furthermore, depending on the amount of first constituent in the fluidto be separated, the size of the first and second sub-cavities andsettling region may be varied accordingly. If only a very minor amountof second constituent is to be separated, the size of the passages 72can be diminished so that this passageway does not become flooded withthe first constituent.

Additional control can be provided by controlling the flow of fluid tobe separated entering the inlet 58 by using for example a valve.Controlling the flow of separated fluid including the second constituentexiting by the pipe 54 can be controlled such as by using another valve.Furthermore, separated first constituent exiting by pipe 56 can also becontrolled by, for example using yet another valve. Using these variouscontrol mechanisms, the degree of separation of constituents in thefluid to be separated can be further controlled.

Referring to FIG. 6 there is shown another embodiment of the presentinvention, with a separator 110 which includes a body 112 rotatablymounted to a shaft 114. Preferably the shaft 114 is split into a firstsection 138 and a second section 140 with a gap 142 between the twosection 138 and 140. Furthermore the shaft is preferably hexagonal incross-section so as to be keyed with receiving coupling collars 152 and154 of the body 112.

The body 112 is formed of a first part in the form of a disc 172 and asecond part in the form of a disc 158. The discs 172 and 158 tapertowards one another along a radial line extending from the shaft 114.The disc 172 is fixably, slidably coupled to the shaft section 138 bycoupling collar 152. The disc 158 is fixably, slidably coupled to theshaft section 140 by coupling collar 154. A cavity 116 is providedwithin the body 112 between the discs 172 and 158. Extending into thecavity 116 from the coupling collar 152 is a divider 118 in the form ofa planar disc having a circumferential edge tapering to a point. Thetapering of the first and second discs also causes the cavity 116 totaper radially away from the shaft 114. The divider 118 divides thecavity 116 into a first sub-cavity 120, and a second sub-cavity 122,with a collection region 124 joining the first sub-cavity 120 to thesecond sub-cavity 122. The collection region 124 commences from thecircumferential edge of the divider 118.

An inlet 126 is provided into the first sub-cavity 120. The inlet 126may by in the form of a raceway into which a pipe can extend to insertfluid to be separated into the separator 16. Other forms of inlet may beprovided as would be suitable for the particular application of theseparator 110. One alternative is described below in relation to FIGS.21 to 25.

A first outlet 130 leads from the collection region 124. The outlet 130is provided by a gap between each of the discs 172 and 158. A secondoutlet 128 leads from the second sub-cavity 122 out of the body 114 ofthe separator adjacent the shaft 114.

It is preferred to have the circumferential edge of the divider 118 asfar away from the shaft 114 as possible. Although, the distance of theedge from the outlet 130 may provide a method of controlling the amountof separation occurring.

Referring to FIGS. 7 and 8, a lower part 146 of the separator 110 isdescribed in more detail. The second section 140 of the shaft 114 can beseen extending through coupling collar 154. Extending upwardly from thecoupling collar 154 is another collar 166. The inside surface of thecollar 166 is spaced from the second shaft section 140 to form a socket174. Within an inside surface of the second disc 158, near the shaft114, is an annular funnel 170. The funnel 170 extends underneath thecollar 166 and leads to a plurality of channels 164 that form the secondoutlet 128. Radially extending from the collar 166 are a plurality ofbaffles 150 (similar to the fins of the previous embodiment). Each ofthe baffles 150 tapers along its length away from the shaft 114 so as toconform with the inside surface of the second disc 158. Each of thebaffles 150 is fixed to the second disc 158 by grub screws 160. At aperimeter of the second disc 158 is a raised portion having a surface168. The surface 168 is perpendicular to the length of the shaft 114. Acorresponding surface 180 is provided on the first disc half 172 asshown in FIG. 9. An O-ring 162 extends around the raised portion so thatit protrudes from the surface 168 and is recessed within the raisedportion.

Referring to FIGS. 9 and 10 an upper part 144 of the body 112 is shown.A first section 138 of the shaft 114 is shown coupled to the couplingcollar 152. The shaft section 138 extends part way through the inside ofthe collar 152. A shaft socket 182 formed in the lower part of thecollar 152. The shaft socket 182 is for receiving a portion of thesecond shaft section 140 that protrudes past the second half 146 of thebody 112 as mentioned in relation to FIG. 8. When the first half of thebody mates with the second half of the body a separation gap 142 isprovided between each of the shaft sections 138 and 140. A gap is alsoformed at the first outlet 130 between surfaces 168 and 180. The degreeof insertion of the second shaft section 140 into the shaft socket 178can be adjusted, which determines the size of the separation gap 142,the size of the second sub-cavity 122 and importantly the distancebetween the surfaces 168 and 180 and thus the size of the first outlet130.

Coupled to the socket section of the coupling collar 152 is the divider118. A diverter 178 is attached to the coupling collar 152 for divertingfluid to be separated into the first sub-cavity 120 through the inlet126. A series of holes 186 extend into the diverter 178 for attachingthe divider 118 by grub screws 160. Extending between the first disc 172and the divider 118 are a series of radially extending baffles 148. Thebaffles 148 have holes 186 for receiving grub screws 160 to attach tothe divider 118 and the first disc 172.

The baffles 148 are shown in isolation in FIG. 11, with each baffle 146being shaped to sit between the first disc 172 and the divider 118. Acurved edge 188 is shown. The curved edge 188 minimises turbulence inthe fluid to the separated as it enters through the inlet 126.

The divider 181 is shown in isolation in FIG. 12. The circumferentialedge 184 is indicated. A hole 190 is for the divider 118 to slide overthe coupling collar 152.

A set of second baffles 150 is shown in FIG. 13 attached to the collar166, which has a hole 192 within forming the socket 76 and for receivingthe coupling collar 154.

Referring to FIG. 17 an example of an assembly for operating theseparator 110 is shown. The assembly includes a frame 220 within whichis housed the separator 110. The separator 110 is orientated so that theshaft 114 extends vertically with the inlet 126 situated above thesecond outlet 128. It is noted that the separator need not operate inthat orientation, although it would generally be preferred to operate inthis orientation. The separator shaft 114 is mounted to the frame 120 bya bearing. A pulley or spindle 230 is coupled to the shaft 114. Thebottom of the shaft 14 sits on a thrust bearing which in turn sits upona jack 228. The jack assembly 228 is able to raise the second section140 of the shaft and thus alter the size of the separation gap 142 andthus the distance between the first half 144 of the body in relation tothe second half 148 of the body and in particular the gap that forms thefirst outlet 130. The pulley or spindle 230 is connected via a drivebelt 232 to another pulley 230 mounted on the end of a motor 222.Accordingly the motor 222 is able to rotate the shaft 114 and thus thebody 112 of the separator 110. Controlling the speed of the motorcontrols the rotation of the separator 110. A feed tank 224 feeds fluidto be separated into the separator into the inlet 126 of the separator110 via a pipe 226. A collection means (not shown) is provided at eachof the outlets.

It will be appreciated that a variety of assemblies may be used,depending upon the particularly application of the separator.

Referring to FIG. 18, the jack assembly 228 is shown in more detail. Itcan be seen that the second section of the shaft 140 has a spigotprojecting into a thrust bearing 240. A roller bearing 242 providesadditional stability to the shaft section 140. A mounting plate 245houses the bearings 240 and 242. The mounting plate 245 sits on a column248, which is slidable within a sleeve 246. The sleeve 246 is coupled toa base 254, which is in turn bolted to the frame 220. A threadedextendable/retractable member 250 of a jack is able to raise or lowerthe column 248 within the sleeve 246 by rotating a crank coupling 252(using a cranking handle) geared to the member 250. A collection means244 extends from a top of the mounting plate 245 to collect fluidexiting the second outlet 128. It can be seen that if the shaft section138 is not permitted to move vertically then the adjustment of the jackwill cause the shaft section 140 to move relative to the shaft section138, which in turn adjusts the distance between the first part 144 andsecond part 146 of the separator and in particular adjusts the gap whichforms the first outlet 130.

Also in this figure, it can be seen that the baffle 148 extends furthertowards the collection region 124 than the baffle 148 shown in FIG. 6.Also in this embodiment minor variations are made to the collar 166.

Referring to FIG. 19, the method of use and operation of this embodimentof the present invention is described. Fluid to be separated enters theinlet 126 of the separator 110 from pipe 226.

The shaft 114 is rotated as indicated by the arrow C. Fluid entering thecavity encounters baffles 148 and is imparted with rotational momentumas the fluid moves towards the collection region 124. The baffles 128impart angular velocity to the fluid and serve to reduce turbulence inthe fluid, which otherwise slips against the rotating body and shearscausing turbulence. As the fluid reaches the end of the divider 118particles entrained within the fluid have centrifugal force exerted onthem and tend to collect in the collection region 124 under what is ineffect high artificial gravity. The particles tend to settle over thefirst outlet 130 within the collection region 124. Depending on theoperation required, the particles are collected or allowed to exit theseparator via the outlet 130 continuously or in batches. Fluid is morereadily able to make a sharp turn around the circumferential edge of thedivider 118 and travel into the second sub-cavity 122. Fluid tends to dothis rather than particles due to the high centrifugal forces whichcause particles (or fluid) having a higher specific gravity to settle inpreference to fluid or other particles having a lower specific gravity.It is also noted that in the collected region 124 it is desirable tokeep turbulence to a minimum to allow the specific gravities to sort theparticles and fluid.

Under the influence of normal gravity or back pressure or suction, fluidhaving a lower specific gravity tends to move through the secondsub-cavity 122 past the baffles 150 towards the outlet 128. As the fluidsubstantially devoid of particles moves towards the shaft it releasesrotational energy to the baffles 150 so that energy is conserved by theseparator and fluid exiting the second outlet 128 is less turbulent.Fluid is then able to exit the second outlet 128 where it is collectedby a collection means 244. The collection means 244 may simply be in theform of an annular cup, which drains via a pipe 260.

With a continuous flow of fluid to be separated into the separator,continual depositing of particles occurs. Particles collecting in thecollection region 124 are compressed together and slowly moves throughthe outlet 130.

Smaller particles will tend to displace fluid between larger particlesas they settle. The displaced fluid improves lubricity between particlesand effectively jostles them further assisting the compacting process.The gap between the surfaces 168 and 180 controls the size of the outlet130 and thus the rate at which particles can exit. Generally this gapwill be very small. Particles may be in a thick paste like state withminimal fluid and will ooze through the outlet 130. It is important tocontrol the rate of outlet of the particles through the outlet 130 tominimise turbulence within the collection chamber 124 and allow settlingof the particles. This may require the size of the separation gap 142being varied through phases to allow adequate collection of particlesbefore their release through the outlet 130. Once released due to thehigh centrifugal force exerted on the particles they will tend to flyfree where they may then be collected within a C-shaped annularcollection means 262 and then drained by an outlet pipe 264 or bedisposed of in some other manner.

In some instances the particles are to be kept and the fluid is to bediscarded and in other instances the particles discarded and the fluidis kept and in yet other cases both the fluid and particles are keptdepending on the application of the separator. The output of the firstand second outlets can be dealt with appropriately.

It is noted that when describing the operation of the separator the term“particles” is used to refer to solids, liquids or gasses that havehigher specific gravity or higher settling velocity than the otherconstituent of the fluid to be separated, which may also be a solid,liquid or gas. In some instances there may also be a carrier fluid,particularly where solid particles are to be separated from other solidparticles each having different specific gravities or particle sizes. Itis noted that separation can be conducted by specific gravity or byparticle mass or by particle size. The speed of rotation of theseparation is believed to control the type and rate (effectiveness) ofseparation. The flow rate of fluid into or out of the separator can alsobe controlled, which can also control the rate of separation.

Referring to FIG. 14, another alternative collection means 204 is shownin schematic form. The collection means 204 is in the form of a member194 which is a grotesque J-shape in cross section. The member is coupledto the outside of the second disc 158 by grub screws 202. A gap 196 isprovided between the outlet 130 and the member 194. Also, the gap 196extends around the back of the J and is curved to leave a gap 200between the member 194 and the disc 172. This allows particles that haveexited the outlet 130 to collect within the gap 196 and build up. Thegap 196 can then be drained via a raceway.

Referring to FIG. 15, another schematic variation of a collection meansis shown. In this embodiment, the member 194 is affixed to the disc 172by the grub screws 202. Particles that have exited the outlet 130accumulate in the gap 196, where they accumulate and flow down the back198 of the J member 194 and then drip under the influence of gravityinto a collection tray.

Referring to FIG. 16, an alternative separator is shown with an enlargedcollection region 214. In this case the discs 172 and 158 together havea bulb portion 108. The inside of the bulb portion 208 serves to enlargethe collection region 214. In addition, the divider 118 is provided witha first flange 210 and a second flange 212 which extend in oppositedirections at an angle of approximately 60° to the plane of theremainder of the divider 118. Both flanges 210 and 212 provide afork-like appearance to the circumference of the divider 118. Each ofthe flanges 210 and 212 end in a ridge, around which the fluid to beseparated must travel. This assists in separation of the particles fromthe remainder of the fluid. It can therefore be seen that fluidentrained with particles 132 that enters the inlet and is then subjectedto centrifugal force by the separator tends to have particles 136collect within the larger collection region, which tapers towards thesecond outlet 130. Fluid substantially devoid of particles 134 may thenleave via the second outlet. This apparatus can assist where thespecific gravity of the particles is similar to the fluid and where theparticles would tend to float within the collection region rather thenbeing separated according to their specific gravity. In this case theyhave a greater time to dwell in the collection region and can thereforeclump together. Clumping tends to reduce their tendency to float orhover in the collection region 124. They will therefore effectively“sink” into the mass of the rest of the particles which will then tendto continue to compact them together as they move towards the outlet130.

Increasing the size of the collection region 24 can affect the timeparticles have to settle. This therefore provides a means of controllingthe particle settling time.

Referring to FIG. 20, an alternative to the separator of FIG. 16 isshown. In this case, the outlet 130 is covered by member 194, J shapedin cross section, which loops over to overlap with a lip 195 on theother side of the outlet 130. The overlapping of member 194 has theadvantage of providing a seal between the inwardly extending part 198 ofthe member 194 and the lip 195 when the upper and lower parts areseparated somewhat. In some cases, particularly when the speed ofrotation is great (or the diameter of the discs are large) hydrostaticforces can force the seal 162 to fail. In this case the forcespressuring the discs to part only serve to assist in sealing between 195and 198.

The build up of collected particles 136 can be released in batches,either via outlet 130 or by flushing out of outlet 164.

It can be advantageous to seal the inlet and outlets from the atmosphereso that the cavity is completely full of fluid in use. Pressurising thefluid flow can further assist this.

Referring to FIG. 21, there is shown another embodiment, separator 110′.The separator 110′ has many similar features to the separator 110. Likenumerals represent like features. The following description concentrateson the differences between separator 110 and separator 110′. Separator110′ includes a body 112 rotatably mounted to a shaft 114. Shaft 114 issplit into a first section 138 and a second section 40. The majority ofthe body 112 is disposed between the two section 138 and 140.

The body 112 is formed of a first bowl shaped disc 172 and a secondplanar disc 158. A part of the disc 172 tapers towards disc 158. Thedisc 172 is coupled to the shaft section 138. The disc 158 is coupled tothe shaft section 140.

A cavity 116 is provided within the body 112 between the discs 172 and158. Extending into the cavity 116 is a divider 118 in the form of athick planar disc having a tapering circumferential edge substantiallyparallel with the tapering part of the disc 178. The divider 118 dividesthe cavity 116 into a first sub-cavity 120, and a second sub-cavity 122,with a collection region 124 joining the first sub-cavity 120 to thesecond sub-cavity 122. A second divider 285 extends radially from theaxis of rotation between the first divider 18 and the second disc 158. Athird cavity 284 is provided between the first divider 118 and thesecond divider 285. The second cavity 122 is defined by the void betweenthe second divider 285 and the disc 158.

An inlet 126 is provided into the first sub-cavity 120 from a pipe orchannel 260 within the inside of the shaft section 138. A separationzone 125 is defined between the commencement of the taperingcircumferential edge of the divider 118 and the second disc 158. A firstoutlet 130 leads from the collection region 124. The outlet 130 isprovided by a gap between each of the discs 172 and 158. The outlet isshown to be closed by a seal 286. A second outlet 128 leads from thesecond sub-cavity 122. The outlet 128 is formed by a sleave 165 over theshaft section 140. A third outlet 274 leads from the third cavity 284.The third outlet is in the form of tube or channel extending through theinside of the shaft section 140. An entry 281 to the third cavity 284leads from the separation zone 125. The second divider 285 includes aparting means in the form of a circular knife 270. The knife 270 has ablade tip 278 pointing towards the direction of flow of fluid in thecollection region 116. This will part the flow of fluid, with fluidcloser to the axis of rotation entering the third cavity 284, throughthe entry 281, and fluid further away from the axis of rotation enteringthe second cavity 122 or collection region 124.

The position of the blade tip 278 can be moved by placing more or lesscircular shims 280 between the knife 270 and the planar body of thesecond separator 285.

The second disc 158 is fixed in relation the first disc 172. An A-frame(in cross-section) support 262 is longitudinally movable in relation tothe shaft 114. The support 262 abuts a thrust washer 266 which in turnabuts an internally threaded collar 264. The collar 264 is akin to a nutthat screws onto a threaded bolt, with the equivalent of the bolt beingan external thread 268 located on the sleave 265. By rotating the collar264 the position of the support 262 and thus the disc 158 may bealtered. Alternative means for moving the support 262 can be provided asappropriate. Such alternatives may include mechanised or hydraulic meansthat can move the support 262 while the separator 110′ is rotating.

Extending between the first disc 172 and the divider 118 are a pluralityof radially extending baffles or fins 148 that follow the contour of thefirst cavity 120. Extending between the first divider 118 and the seconddivider 285 are a plurality of radially extending baffles or fins 272that follow the contour of the third cavity 284. Extending between thesecond divider 285 and the second disc 158 are a plurality of radiallyextending baffles or fins 150 that follow the contour of the secondcavity 122.

Referring to FIG. 22, in use particles under the influence ofcentrifugal forces are driven towards the inside surface of taperedportion of the first disc as they travel through the separation zone125. The particles 292 are shown collecting the in the collection region124. In this embodiment the separator is configured to collect particlesin a batch mode. Once enough particles are collected in the collectionregion, or the batch of fluid has been processed, the outlet 130 may beopened to allow the particles to be removed. The flow of fluid from thesecond outlet 128 can be used to detect the filling of the collectionregion 124.

The seal of the outlet 130 is in the form of a circular sealing member286 that is coupled to the perimeter of the second disc 158 by aflexible bridging member. The sealing member 286 is coupled to thesupport 262. The sealing member 286 may be inserted in a circular recess288 provided in outer end region of the first disc 172 by moving thesupport 262. In doing so, the bridging member will flex. The sealingmember 286 may be in the form of a reinforced rubber ring having anoversized insert 290 at the inner edge of the bridging member forthreading in a keyway of the second disc 172. The ring may be fixed tothe support 262 by an adhesive and or mechanical means. The sealingmember 286 forms a seal at the outlet 130 when inserted in the recess288.

Referring to FIG. 23, an alternative form of outlet 130 is shown. Theseal of the outlet is in the form of a flexible, resilient, member 294coupled to the second disc 158. The member 294 normally extendssubstantially parallel to the second disc 158. The member 294 has a head296. A correspondingly shaped (semi-circular in cross-section) recess298 is provided in the end region of the first disc 172. The support 262includes a positioning tip 300. When the support 262 is moved towardsthe second disc 158, the tip 300 engages with and pushes the member 294towards the recess 298. This closes the outlet 130 until the head 296 istightly pushed into the recess 298, whereupon the outlet 130 is sealed.If the support 262 is moved away from the second disc 158, pressure onthe head is released and the seal ends. The outlet opens as the member294 returns to its normal position. Any particles settled in thecollection region 124 may be removed. If the particles are tightlypacked they may not be inclined to exit. The passage 302 through theoutlet 130 may be tapered to expand in volume radially to assist inremoval of collected particles.

Referring to FIGS. 24 and 25, another alternative form of outlet 130 isshown. The seal of the outlet is also in the form of a flexible member308 that extends between the second disc 158 and a circular flange 304.The flange 304 extends from the support 262 toward the first disc 172. Abacking member 306 supports the back of the member 308 when the outletis closed. The backing member 306 is in the form of an inclined ringfixed to the support 262 and flange 304. A circular recess 288 providedin outer end region of the first disc 172 for receiving tip of theflange 304. A surface 310 is angled to abut the member 308 when theoutlet is fully closed to form a seal between the first disc 152 and themember 308.

As the support 262 is moved towards the second disc 158, the tip of theflange 304 engages with recess 288. This closes the outlet 130 with themember 308 providing a seal. The member 308 is supported by the backingmember 308. If the support 262 is moved away from the second disc 158,the flange 306 parts from the recess 288, the backing member 306 partsfrom the back of the member 308 and the member 308 moves away from thesurface 310. The outlet opens as the member 308 continues to move awayfrom the surface 310. Any particles packed/settled in the collectionregion 124 may be removed. The passage 302 through the outlet 130 istapered to expand in volume radially to assist in removal of collectedparticles.

The inner layer of fluid parted by the parting means 270 may not betotally devoid of particles. If this is the case particles may beinclined to settle if the dwell time of the fluid flow is sufficient,such as in places where the flow is subject to eddying. In FIG. 21 onthe right hand side the parting means 270 provides a sharp bend in thepassage into the third cavity 284. On the left hand side the drawing ismodified to show an arrangement to stop settling of particles from thefluid that has been parted from the rest of the fluid flow. If particleswere allowed to settle, then the build up could provide clogging orblockage of the flow. The arrangement to prevent settling of particleshere is shown in more detail in FIG. 24.

At a bend 283 in the passage between the outermost circumferential tipof the first divider and the parting means 270, the passage is narrowedby providing a curved surface 282 of the parting means 270 closer to thefirst divider 118 than the gap between the knife tip and the divider 118and the thickness of the third cavity 284. This will cause the fluidflow to speed up as it moves though a reduced volume. Due to theincrease in velocity of the fluid (jetting) any particles remaining inthe fluid will be less inclined to settle.

The method of use of the separator 110′ is similar to separator 110.Fluid to be separated is enters the inlet 126. The shaft 114 is rotated.Fluid entering the cavity encounters baffles 148 and is imparted withrotational momentum as the fluid moves radially though the first cavity120. As the fluid reaches the tapered part of the divider 118 particlesentrained within the fluid have centrifugal force exerted on them andtend to layer on the inner surface on the first disc 172. The partingmeans 270 separates the flow of fluid with fluid having less particlesentering the third cavity and fluid having more particles entering thecollection region 124. Still under the influence of the centrifugalforce the particle entrained in fluid in the collection region 124 tendto settle over the first outlet 130. Depending on the operation requiredthe particles by be collected or allowed to exit the separator via theoutlet 130 continuously or in batches.

It is noted that in the separator 110′, if the first outlet is closed,the second outlet effectively operated as an open first outlet in theseparator 110 and the third outlet of separator 110′ effectivelyoperates as the second outlet of separator 110. In addition collectedparticles can be removed in batches from the first outlet.

Fluid substantially devoid of particles moves towards the axis ofrotation releases rotational energy to the baffles 150 or baffles 272 sothat energy is conserved by the separator and fluid exiting the secondoutlet 128 or third outlet 274 is less turbulent.

The advantages of the present invention will be clear to the skilledaddressee. These include:

-   -   a screen or filter is not involved and therefore does not need        to be cleaned, in effect the separator of the present invention        is self cleaning;    -   the separator need not be operated in a particular orientation,        although it may be preferred to use the influence of gravity to        assist the fluid moving from the inlet down to the first outlet;    -   due to the control provided at the first outlet the collection        of particles within the collection region need not always by        operated in batches, although it may be operated as such;    -   controlling the outlet of particles from the collection region        also assists in better separation and therefore the separator of        the present invention is highly efficient; and    -   energy used to rotate the separator and fluid passing        therethough is conserved by recovering the rotational energy        imparted on the fluid as it travels through the second        sub-cavity.

Modifications and variations may be made to the present inventionwithout departing from the basic inventive concept. Such modificationsmay include:

-   -   altering the method of control of the rate of constituent        leaving the first outlet;    -   altering the orientation of the separator in use;    -   changing the relative size of the cavity so that it may be        shorter and wider (more disc like) or longer and thinner (more        cylinder like);    -   in addition a series of separators may be provided to        progressively refine the separation of the outlet of one        separator by the operation of a second separator;    -   the number of baffles/fins may vary to the point where a large        number of baffled are provided so that in effect the cavity may        become a series of radially extending channels rather than voids        with baffles extending therein.

Such modifications and variations are intended to fall within the scopeof the present invention, the nature of which is to be determined fromthe foregoing description.

1. A centrifugal separator for separating separable constituents of afluid to be separated, including: a body rotatable about an axis, thebody having a cavity therein; a divider dividing the cavity into a firstsub-cavity arranged for fluid to flow in a direction having a radialcomponent and a second sub-cavity arranged for fluid to flow in adirection having a component that is towards the axis of rotation; aninlet leading into the first sub-cavity at or near the axis of rotationof the body; a first outlet in communication with a settling region ofthe cavity between or connecting the first sub-cavity to the secondsub-cavity; and a second outlet leading from the second sub-cavity at ornear the axis of rotation of the body; whereby in use, fluid to beseparated enters the cavity via the inlet, rotation of the body and thefluid therein causes a centrifugal force to be applied to fluid flowingthrough the cavity, a first constituent of the fluid tends to collect inthe settling region and a second constituent of the fluid tends to flowinto the second sub-cavity, the second constituent in the secondsub-cavity exits the cavity via the second outlet and the firstconstituent collected in the settling region exits the cavity via thefirst outlet.
 2. A centrifugal separator according to claim 1, wherein athird sub-cavity connects the settling region to the first outlet.
 3. Acentrifugal separator according to claim 2, wherein the third sub-cavityis arranged for fluid flow in a direction having a component that istowards the axis of rotation of the body.
 4. A centrifugal separatoraccording to claim 1, wherein the first outlet is at or near the axis ofrotation.
 5. A centrifugal separator according to claim 2, wherein thethird sub-cavity is separated into a plurality of chambers by dividingwalls, with each chamber extending towards the axis of rotation.
 6. Acentrifugal separator according to claim 1, wherein the size of thecavity decreases radially from the axis of rotation.
 7. A centrifugalseparator according to claim 1, wherein the divider is shaped such thatthe size of the first sub-cavity increases along the path of flow offluid though the first sub-cavity.
 8. A centrifugal separator accordingto claim 1, wherein the divider is shaped such that the size of thesecond sub-cavity decreases along the path of flow of fluid through thesecond sub-cavity.
 9. A centrifugal separator according to claim 1,wherein the divider is shaped to space the first sub-cavity from thesecond sub-cavity.
 10. A centrifugal separator according to claim 1,wherein the first sub-cavity is provided with a plurality of radiallyextending fins.
 11. A centrifugal separator according to claim 10,wherein the first sub-cavity is divided into a plurality of chambers bythe fins.
 12. A centrifugal separator according to claim 10, wherein thesecond sub-cavity is provided with a plurality of radially extendingsecond fins.
 13. A centrifugal separator according to claim 12, whereinthe second sub-cavity is divided into a plurality of chambers by thesecond fins.
 14. A centrifugal separator according to claim 12, whereineach first fin is integrally formed with a corresponding one of thesecond fins.
 15. A centrifugal separator according to claim 1, whereinthe separator includes a drive means for rotating the body.
 16. Acentrifugal separator according to claim 1, wherein the speed ofrotation of the body is controlled, whereby the extent of separation ofthe constituents can be controlled.
 17. A centrifugal separatoraccording to claim 1, wherein the separator includes a means forcontrolling the rate of flow of fluid to be separated in through theinlet.
 18. A centrifugal separator according to claim 1, wherein theseparator includes a means for controlling the rate of flow of fluidfrom the first outlet.
 19. A centrifugal separator according to claim 1,wherein the separator includes a means for controlling the rate of flowof the fluid from the second outlet.
 20. A centrifugal separatoraccording to claim 1, wherein a shaft extends through the axis ofrotation, the body arranged to be rotated by rotation of the shaft. 21.A centrifugal separator according to claim 20, wherein the shaft extendsthrough the body.
 22. A centrifugal separator according to claim 1,wherein the settling region includes a collection region for holding thecollected first constituent until it is removed via the first outlet.23. A centrifugal separator according to claim 22, wherein thecollection region is spaced from the axis of rotation.
 24. A centrifugalseparator according to claim 1, wherein the body is substantially discshaped.
 25. A centrifugal separator according to claim 1, wherein thebody includes a first disc shaped part and a second disc shaped part.26. A centrifugal separator according to claim 25, wherein the discs areseparable.
 27. A centrifugal separator according to claim 26, whereinthe first outlet is provided by a gap between the body parts when theparts are separated.
 28. A centrifugal separator according to claim 27,wherein the size of the gap is adjustable.
 29. A centrifugal separatoraccording to claim 24, wherein the divider is in the form of a radiallyextending planar disc.
 30. A centrifugal separator according to claim29, wherein in one embodiment a circumferential region of the dividerincludes a first flange extending transversely to a radial lineextending from the axis of rotation.
 31. A centrifugal separatoraccording to claim 30, wherein the circumferential region includes asecond flange extending transversely to the radial line from the axis ofrotation and at an angle to the first flange greater than the angle ofthe first flange to the divider.
 32. A centrifugal separator accordingto claim 1, wherein the inlet is provided with a raceway.
 33. Acentrifugal separator according to claim 1, wherein the first outlet isprovided with a raceway.
 34. A centrifugal separator according to claim1, wherein a separation zone precedes the collection region in thecourse of flow of fluid.
 35. A centrifugal separator according to claim34, wherein the separation zone is divided into an inner separation zoneand an outer separation zone by a parting means.
 36. A centrifugalseparator according to claim 35, wherein the parting means is a circularknife.
 37. A centrifugal separator according to claim 34, wherein thecollection region follows the outer separation zone in the course offlow of the fluid.
 38. A centrifugal separator according to claim 35,wherein a third outlet leads from the inner separation zone.
 39. Acentrifugal separator according to claim 27, wherein the first outlet isclosed and sealed by a seal in the gap between the parts of the bodywhen the gap between the parts is closed.
 40. A centrifugal separatoraccording to claim 27, wherein the first outlet is open when the gapbetween the parts is opened.